Download PDF
Synfacts 2006(7): 0674-0674  
DOI: 10.1055/s-2006-941871
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart · New York

Regioselective Pyrrole Oxidative Dimerization

Contributor(s): Timothy M. Swager, Anne J. McNeil
T. Dohi, K. Morimoto, A. Maruyama, Y. Kita*
Osaka University, Japan
Further Information

Publication History

Publication Date:
22 June 2006 (online)

    Permissions and Reprints

Significance

Kita and co-workers prepared a series of bipyrroles through the regioselective, phen­yliodine bis(trifluoroacetate) (PIFA)-mediated oxidative coupling of pyrroles. These authors recently reported a similar procedure to generate head-to-tail 3-alkylthiophene dimers using PIFA/TMSOTf (Chem. Commun. 2005, 2930-2932). The pyrrole coupling, however, requires a milder Lewis acid (TMSBr) to obtain high yields. Although the mechanism has not been investigated, the authors propose a pyrrole radical cation intermediate. Notably, electron-deficient pyrroles are unreactive and N-phenyl pyrrole yields exclusively the 2,3′-bipyrrole in 56% yield.